What are these colorful cards?
They're "Fight Cards" for the Sonic the Fighters arcade game. Each character card has a moves-list on the back that tells you the buttons & sequence you need to get each special move/etc to activate. Each card has 1 character so you'd have to collect them all. At the time of release, this type of thing would be very important for beating the arcade game because you had to pay for each play & there wasn't really the internet to just go and look up everything. All the instructions are in Japanese though, so you can't read them. They do make a cool collectible today though. But, how would these have been distributed?